The Australian Bureau of Meteorology uses stacked transparent gifs for their rain radar images. This means you can’t just link to the latest radar image on their site – if you do, you get something that looks like this:
They’ve done this for entirely legitimate reasons. Because the final image you see on the page is a composit of stacked transparent layers, it means you can configure what layers you see without their servers having to deliver a slightly tweaked version of the large rainfall gif.
Annoyingly, this means it’s hard to post a rainfall gif in something like slack. To that end, I made a solution:
The script at that url (https://bom.caseyfulton.com) fetches all the requisite images and composites them into a single gif using the PHP GD library.
Check out the code on GitHub: https://github.com/caseyfw/bom-gif